(Carlo Alberto Conti/Moment/Getty Images)
There's a strange anomaly in the North Atlantic, just south of Greenland: A 'cold blob' of ocean and air that's cooling down while the rest of the world warms up.
Now a new analysis of this cold blob points to a serious and imminent climate problem.
An international team of researchers used satellite data, reanalysis records, and ocean heat content data, including records extending back to 1955, to try to figure out the driving forces behind the blob.
Up to this point, there have been two schools of thought: either ocean currents are bringing less heat into the region, or the ocean in that area is losing more heat through the surface.
Their results support the first explanation, and they conclude that we're now very close to a dangerous tipping point.
https://www.youtube.com/watch?v=p4pWafuvdrY
The Atlantic's cold blob is a sign of weakening of the Atlantic Meridional Overturning Circulation (AMOC), the researchers conclude.
This is showing signs of shutting down entirely – an event predicted to have consequences for the planet far more severe than a cold patch in the ocean.
"Given the well-established existence of a tipping point of the AMOC, as well as recent studies finding a range of different 'early warning signals' of the ocean circulation approaching such a tipping point, the strong evidence for a weakening AMOC is a serious concern for society and policy," write the researchers in their published paper.
The researchers determined that the cooling was a deep, underwater current issue. Surface heat loss in the area has actually decreased, the study shows, so it's not that more heat is escaping – it's that less heat is coming in.
Considering that the cold patch of ocean sits right at the top of the swirling 'conveyor belt' of water that is the AMOC, it makes sense that temperatures here would drop as the AMOC weakens, and pushes less warm water from the tropics and equator farther north.
(Rahmstorf et al., Geophys. Res. Lett., 2026)
That the AMOC is slowing and weakening has been established by previous studies. This new research gives us some of the best evidence yet that the cold blob and this vast ocean current are directly related.
This conclusion aligns with a 2025 study that used climate models rather than historical, real-world data to link the AMOC to the region of cooler water, also known as the North Atlantic warming hole.
"The observed cooling trend cannot be explained by surface heat flux changes," write the authors of this new study.
"Multidecadal heat content variations are generally larger and more tightly correlated with ocean heat transport than with surface heat flux variability."
With this underlying reason for the Atlantic's cold blob now settled, what comes next? Unfortunately, based on the best models we have, it's not looking good: Scientists broadly concur that the AMOC is inching closer to a tipping point in its weakening influence, and will eventually disappear.
A combination of warming ocean waters and melting glaciers (which release freshwater into the oceans) is changing the balance that keeps the AMOC running.
If it were to shut down entirely, Europe would be expected to experience much colder, harsher winters, with significant changes in global weather patterns, ecosystems, and food security.
That the AMOC is slowing and weakening has been established by previous studies. This new research gives us some of the best evidence yet that the cold blob and this vast ocean current are directly related.
This conclusion aligns with a 2025 study that used climate models rather than historical, real-world data to link the AMOC to the region of cooler water, also known as the North Atlantic warming hole.
"The observed cooling trend cannot be explained by surface heat flux changes," write the authors of this new study.
"Multidecadal heat content variations are generally larger and more tightly correlated with ocean heat transport than with surface heat flux variability."
With this underlying reason for the Atlantic's cold blob now settled, what comes next? Unfortunately, based on the best models we have, it's not looking good: Scientists broadly concur that the AMOC is inching closer to a tipping point in its weakening influence, and will eventually disappear.
A combination of warming ocean waters and melting glaciers (which release freshwater into the oceans) is changing the balance that keeps the AMOC running.
If it were to shut down entirely, Europe would be expected to experience much colder, harsher winters, with significant changes in global weather patterns, ecosystems, and food security.
https://www.youtube.com/watch?v=zauJQzti7FQ
"While large uncertainty remains over how close the Earth is to this tipping point, standard CMIP6 simulations of future global warming scenarios suggest it is crossed in a substantial subset of these model simulations around the middle of this century," write the researchers.
The AMOC has only been directly monitored since 2004, leaving scientists with too short a record to clearly determine the long-term trajectory of its recent weakening.
Using climate models like those in CMIP6 (Coupled Model Intercomparison Project Phase 6), we can at least prepare for and predict what might happen if the AMOC stalls – as multiple studies are now suggesting.
"This risk requires urgent attention by policymakers," conclude the study authors.
The Life of Earth
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